The comparison of time reverse modeling and diffraction stacking for the time-spatial localization of microseismic events

This article is referred to the problem of source localization in visco-elastic medium using the results of surface seismological observation. There were investigated three technologies: Time Reverse Modeling, Diffraction stacking and Stacking correlation. The calculation is based on FEM

Determination of moment tensor and location of microseismic events under conditions of highly correlated noise based on the maximum likelihood method

© 2017 European Association of Geoscientists & Engineers.We examine the problem of localization of a single microseismic event and determination of its seismic moment tensor in the presence of strongly correlated noise. This is a typical problem occurring in monitoring of microseismic events from a daylight surface during producing or surface monitoring of hydraulic fracturing. We propose a solution to this problem based on the method of maximum likelihood. We discuss mathematical aspects of the problem, some features and weak points of the proposed approach, estimate the required computing resources, and present the results of numerical experiments. We show that the proposed approach is much more resistant to correlated noises than diffraction stacking methods and time reverse modeling

Zwanzig-Mori projection operators and EEG dynamics: deriving a simple equation of motion

We present a macroscopic theory of electroencephalogram (EEG) dynamics based on the laws of motion that govern atomic and molecular motion. The theory is an application of Zwanzig-Mori projection operators. The result is a simple equation of motion that has the form of a generalized Langevin equation (GLE), which requires knowledge only of macroscopic properties. The macroscopic properties can be extracted from experimental data by one of two possible variational principles. These variational principles are our principal contribution to the formalism. Potential applications are discussed, including applications to the theory of critical phenomena in the brain, Granger causality and Kalman filters

Thermal effect of bainitic transformation in tube steels during accelerated cooling

An original laboratory bench, which allows for modeling technological rates of cooling of hot-rolled sheets in the process of controlled thermomechanical processing (TMCP) has been designed. Samples cut from an industrial sheet of 06G2MB type pipe steel used in production of large diameter pipes with strength grade X80 have been used. Time dependencies of the actual temperature at initial cooling rates of 100 – 500 K / s have been obtained. All processing modes resulted in almost identical structures mainly formed due to the bainitic transformation. The dispersion of structures decreased with the increase of the cooling rate. Thermotechnical calculations were carried out assuming that the temperature equalization over the sample thickness was instant. The times of transformation amounted to 1 – 9 s. Most of the transformation at all cooling modes occurred in conditions close to the isothermal one. The athermal nature of the bainitic transformation in TMCP was recorded. Within the observed interval of cooling rates, the temperature at the starting point of the bainitic transformation was 660 – 730°C. The heat effect approximately was equal to 120 kJ / kg, which is twice larger than the thermal effect of the martensite transformation for low-carbon steels. This fact suggests that the kinetics of the bainitic transformation is largely determined by the energy of the slowest process, namely, the re-arrangement of carbon atoms in the austenite occurring parallelly to the shear transformation of FCC lattice into BCC one. It is assumed that energy contribution of the redistribution process of carbon atoms (if their amount is small) to the thermal effect of the bainitic transformation is comparable, at least, to the energy effect of the shear lattice rearrangement. © 2018, Institute for Metals Superplasticity Problems of Russian Academy of Sciences. All rights reserved.Благодарности/Acknowledgements. Работа выпол-нена на  оборудовании ОАО «Аусферр». Работа выпол-нена в  рамках государственного задания ФАНО России, тема «Структура» (”Structure“), номер госрегистрации 0120146333. Авторы выражают признательность за со-действие программе поддержки ведущих университетов РФ в целях повышения их конкурентоспособности № 211 Правительства РФ №02.А03.21.0006./The study was performed on the equipment from OAO “Ausferr”. The study was performed within the framework of the state assignment from the Federal Agency for Scientific Organizations of Russian Federation, theme “Structure”, registration number 0120146333. The authors express their gratitud

Localization of microseismic events and determination of source parameters

© Published under licence by IOP Publishing Ltd.We examine the problem of localization determining and a microseismic moment tensor of single microseismic event in the presence of strongly correlated noise. This is a typical problem occurring in monitoring of microseismic events from a daylight surface under conditions of a producing field or surface monitoring of hydraulic fracturing. We offer the solution to this problem based on the method of maximum likelihood. The article presents of decision of this problem and the results of numerical experiments. We discuss some features and problems of the proposed approach and estimate the required computing resources. We develop the problem of determination direction of fracture propagation from microseismic event

Determining source mechanism types of the underground event

© 2019 IOP Publishing Ltd. We consider problem determination of focal mechanism and identification the type of source of underground event. This is a typical problem for observing microseismic events, which arise during the reservoir prospecting or hydraulic fracturing. The article presents of recovery of impulse from explosive cord by surface data and application a Hudson plot to determine type of the source

Determining source mechanism types of the underground event

© 2019 IOP Publishing Ltd. We consider problem determination of focal mechanism and identification the type of source of underground event. This is a typical problem for observing microseismic events, which arise during the reservoir prospecting or hydraulic fracturing. The article presents of recovery of impulse from explosive cord by surface data and application a Hudson plot to determine type of the source

The comparison of time reverse modeling and diffraction stacking for the time-spatial localization of microseismic events

This article is referred to the problem of source localization in visco-elastic medium using the results of surface seismological observation. There were investigated three technologies: Time Reverse Modeling, Diffraction stacking and Stacking correlation. The calculation is based on FEM

The comparison of time reverse modeling and diffraction stacking for the time-spatial localization of microseismic events

This article is referred to the problem of source localization in visco-elastic medium using the results of surface seismological observation. There were investigated three technologies: Time Reverse Modeling, Diffraction stacking and Stacking correlation. The calculation is based on FEM

La Patrie : journal quotidien, politique, commercial et littéraire

05 décembre 18941894/12/05 (A54)